The U.S. Military’s New Multi-Orbit Approach To Missile Warning

The U.S. Space Force is attempting a novel approach to space-based missile warning and tracking to counter adversarial weapon systems that are dimmer, faster and more maneuverable than ballistic missiles.

Russia attacked a Ukrainian rocket factory Nov. 21 with a new conventionally armed, medium-range ballistic missile that President Vladimir Putin identified as a Mach-10-capable weapon named Oreshnik, calling the firing a response to strikes on Russian soil by Western-made missiles.

• Space Force and MDA are in “lockstep” over no-fail mission
• Missile tracking is to be handled by MEO and LEO layers

China continues to expand its strategic missile forces, developing a range of air-to-air missiles, conventionally armed ICBMs and increased numbers of nuclear warheads. North Korea is also accelerating ICBM production.

As the Space Force approaches its fifth birthday, one of the U.S. military’s longest-running and most critical on-orbit mission areas is undergoing a facelift costing billions of dollars over the next half-decade.

The nation has enjoyed an uninterrupted space-based early warning capability from geostationary orbit (GEO) since the Missile Defense Alarm System spacecraft launched in the 1960s to detect Soviet ICBMs.

The current architecture includes Lockheed Martin-built GEO-based Space-Based Infrared System satellites and payloads in highly elliptical orbit (HEO), legacy Northrop Grumman Defense Support Program satellites and associated ground systems. Those spacecraft were built to monitor bright, predictable and easily tracked missile-based threats. But the landscape has changed as adversaries develop more sophisticated weapons to use against the U.S.

“These threats are faster, they’re dimmer, they’re highly maneuverable,” Col. Heather Bogstie said at a June conference in Los Angeles, when she was senior materiel leader for missile warning, tracking and defense at Space Systems Command (SSC). “They can carry conventional and nuclear warheads, and we don’t know where they’re going to impact. This is stressing those systems that we’ve had the luxury of time to field.”

For what comes next, the Space Force wants a holistic architecture that includes sensors performing missile warning, missile tracking and eventually missile defense missions in low Earth orbit (LEO) and medium Earth orbit (MEO), as well as GEO and HEO. The Defense Department has set up a combined program office for SSC, the Space Development Agency (SDA) and the Missile Defense Agency (MDA) to integrate the programs that must come together to close the missile threat kill chains.

The multi-orbit architecture hearkens back to the Reagan-era Strategic Defense Initiative, which called for a radical pivot away from the traditional development of a few sophisticated satellites to a proliferation of on-orbit sensors in response to threats such as nuclear anti-satellite weapons and high-energy lasers.

Four new satellites will fulfill the missile warning mission from GEO, with launches scheduled between late 2025 and 2030. The MEO and LEO layers will focus on tracking, with about 30 satellites planned under the SSC-led Missile Track Custody expansion into MEO and nearly 100 LEO satellites to be built by the SDA.

The Space Force is fielding the LEO and MEO elements via a spiral acquisition process, with new capabilities launching into orbit every two or three years—via “tranches” in the SDA and “epochs” in SSC.

The Missile Track Custody MEO Epochs 1 and 2 are focused primarily on missile tracking, but the constellation will eventually integrate missile warning capabilities as the service pivots away from its GEO and HEO layers, Bogstie said, noting that future is a long way off.

“We have this beautiful umbrella of strategic capabilities in GEO and HEO that we’re still fielding, so from a missile warning perspective, those requirements are still being met,” she said.

The Next-Generation Overhead Persistent Infrared (OPIR) program will fill out the future GEO layer. Lockheed Martin is building two satellites with Raytheon-provided payloads under a contract currently valued at $8.2 billion. The Space Force originally awarded Lockheed a contract for a third Next-Generation Geosynchronous spacecraft but pulled it in 2023 after determining the planned LEO and MEO constellations rendered it unnecessary.

Northrop Grumman is building two OPIR polar satellites under a contract cumulatively worth more than $4.1 billion. One spacecraft is expected to launch in late 2028 and the other in 2030.

The Space Force also is fielding a new ground system called the Future Operationally Resilient Ground Evolution (FORGE), designed as a government-owned, modular and cyber-resilient open architecture to process missile warning and tracking data from legacy and future space systems. Raytheon—now part of RTX—is building the ground architecture and made the first software delivery for operations in April to the OPIR Battlespace Awareness Center at Buckley SFB in Colorado.

For the MEO layer, Boeing-owned Millennium Space Systems is building two planes of six satellites each under the Epoch 1 contract, with launches expected between late 2026 and 2027. Raytheon was to build three spacecraft under Epoch 1, but the Space Force cut the contractor from the program in May, citing schedule delays and cost overruns. L3Harris Technologies delivered a payload design under a separate study.

The Millennium offering focuses on a recurring production line, drawing on years of development work on the Boeing payload and Altair platform, says Doug Hulse, program director of the company’s sensing portfolio. The Altair bus is built for multiple U.S. government programs, which allows for commonality and reuse directly at the platform level, he says.

SSC is completing source selection for Missile Track Custody in MEO Epoch 2, which includes up to 18 satellites built under the current Epoch 1 contract. The command expects to spend about $6 billion in R&D funds on the program in 2025-29, as outlined in its fiscal 2025 budget request.

Meanwhile, the SDA is leading the LEO element of the missile tracking architecture via its own proliferated LEO constellation. The agency launched eight Tranche 0 Tracking Layer spacecraft in February that were built by SpaceX and L3Harris. Thirty-two new missile warning and tracking satellites built by Northrop Grumman and L3Harris are scheduled to launch in the spring of 2025 under Tranche 1.

The Tranche 2 Tracking Layer includes 54 satellites due to launch around 2027, with Lockheed Martin, L3Harris and Sierra Space as vendors. The SDA also will launch eight Millennium-built satellites to demonstrate advanced fire control capabilities alongside Tranche 2.

The agency wants industry feedback on the feasibility of a combined missile tracking and defense satellite that would appear in Tranche 3 of the Tracking Layer, SDA Director Derek Tournear said in a November webinar hosted by the Mitchell Institute for Aerospace Studies.

Such an asset would allow the U.S. not only to detect and track a maneuvering missile but also to detect it “to such accuracy that I could send that data down to an interceptor with no other sensors needed,” Tournear said.

The MDA is also involved in the new architecture and in February launched two Hypersonic Ballistic Tracking Space Sensor (HBTSS) prototypes to provide data on fire control quality needed to defeat advanced missile threats. Those prototypes will inform the SDA’s Tracking Layer and provide hypersonic threat tracking data to linked missile defense weapons such as the MDA’s future Glide Phase Interceptor.

The agency is “in lockstep” with its colleagues on the future architecture, MDA Director Lt. Gen. Heath Collins said in June at the Center for Strategic and International Studies. The SDA is “already planning HBTSS-like sensors in their future tranches to start to fill out that truly global hypersonic kill chain for us,” Collins said.

Through the hybrid architecture, the Space Force is ensuring it leaves no gaps in the missile threat coverage, says Todd Harrison, a senior fellow at the American Enterprise Institute.

“Ultimately, this is a mission area with no room for failure,” he tells Aviation Week. “So there’s a bit of overkill in the architecture right now—a bit of redundancy.”

If and when the LEO and MEO layers become operational and provide more resilient 24/7 global coverage, a GEO layer may no longer be necessary, he notes.

But the redundancy is part of the resiliency, Col. Robert Davis, program executive officer for space sensing at SSC, said in a July webinar hosted by the National Security Space Association. “There’s a diversity in the capabilities’ designs,” he said. “If there is a flaw in one or more of those, it’s unlikely to completely affect the architecture.”